Bladder crystals and bladder stones in cats

Written by Anouk | April 23, 2025

Bladder problems are common in cats. Both female and male cats can experience this issue at some point in their lives. The most common problems in cats are bladder infections and bladder stones/crystals.

What are bladder crystals and stones?

Bladder crystals and stones can form in the bladder. These are made up of minerals that have precipitated due to a change in the chemical composition of the urine. The main cause of this is the cat’s diet and drinking behavior. The food often contains too many minerals (especially calcium, magnesium, and phosphate), and the cat drinks too little, which prevents the minerals from dissolving properly.

The acidity of the urine also plays a role. Bladder crystals and stones can rub against the bladder wall and cause an infection. Conversely, a bladder infection can alter the pH of the urine, leading to the formation of bladder crystals.

Different types of bladder crystals and stones

There are several types of bladder crystals and stones that can make life difficult for your cat. Below is a short overview of the different types and how they form:

Struvite: forms in urine with a high pH (alkaline), causing magnesium, ammonium, and phosphate to clump together. Cats that develop struvite often don’t drink well, making them more vulnerable.
Calcium oxalate: forms in urine with a low pH (acidic), causing calcium and oxalate to bind. Cats who develop calcium oxalate are often sensitive to one of these substances.
Cystine: forms in urine when the pH is too low (acidic), though the exact cause is unclear. Often the urine contains an elevated amount of the amino acid cystine. Fortunately, this type is rare in cats.

When are bladder crystals and stones dangerous?

Bladder crystals and stones are among the most dangerous types of urinary issues. Over time, bladder crystals can clump together into stones. These stones can become large enough to block urination or may enter the urethra and cause an obstruction. This is always an emergency! The longer your cat is unable to urinate, the more severe the consequences. Naturally, you want to avoid this!

How to treat bladder crystals and stones?

Once your vet has identified the type of crystal or stone your cat has, a treatment plan will be made. This often starts with medication to relieve any pain or inflammation, combined with a special urinary diet tailored to the specific type of crystal. Pay close attention to the food you choose—not all urinary diets are suitable for every type of bladder crystal or stone.

Some examples of urinary diets for bladder issues are:

Vetality Urinary – Cat Food; for use with struvite
Royal Canin Urinary S/O; for use with struvite and calcium oxalate
Hill’s c/d Urinary Care – Urinary Stress – Prescription Diet – Feline; for use with struvite and calcium oxalate
Specific Kidney Support FKD; for use with cystine

Also read our blog: Which food for bladder crystals in cats?

In addition to urinary food, there are various supplements that can support cats with bladder crystals or stones. Note: not all supplements can be used in combination with urinary diets. Always consult with your own vet about this.

Improving the bladder environment can also help reduce the risk of crystal formation. Dr. Ann’s Urinary Care is an example of this. If you’re looking to specifically support the bladder lining, Vetplus Cystaid might be a good choice.

Still have questions after reading this article? Feel free to contact our veterinary team at [email protected] or send us a WhatsApp message!